The present invention is generally related to pattern dyeing of textile materials or space dyeing of yarn in which the fibers constituting the yarn or textile material have been treated with a finish composition that improves pattern definition and color saturation.
Textile materials, including fabric, cloth, drapery material, velour, velvet, velveteen, corduroy, rugs, carpet and the like are commonly printed with patterns of natural or synthetic dyes by well known processes, such as transfer printing, jet dye injection, screen printing, Kuster printing, and the like. However, despite the success of many of these techniques, undesirable characteristics such as poor pattern definition, low dye yield, and "frostiness", a visual effect in which the surface of the material appears covered in a thin frosting of ice, are the focus of continuing research efforts within the industry. Many of these undesirable characteristics are believed to be due to uncontrolled dye diffusion or moisture transport during the initial transfer of the dyestuff solution to the textile material and during the first moments of the steam treating process that fixes the dye to the fibers that make up the textile material.
Yarns are sometimes dyed using a process referred to as space dyeing. In this process a strand of yarn can be dyed with more than one color at irregular intervals along its length, before the yarn is processed into fabric. Space dyeing of yarn can suffer from some of the same dye pattern definition problems described above with respect to fabric.
Previous attempts to overcome these problems have met with only limited success and acceptance. One approach has been the incorporation into the dyestuff solution of thickeners to reduce or prevent the diffusion of the dyestuff into the fiber. Examples of such anti-diffusion agents include natural and synthetic gums, such as alginates, xanthan gum, guar, starch, carboxymethyl cellulose, natural and synthetic resins and the like. However, the synthetic gum systems are not robust, that is, they are sensitive to salts and metal ions which reduce or degrade the viscosity of the dyestuff solution. This in turn reduces the amount of dyestuff that is actually fixed to the fibers of the textile material, leading to the wasteful use of these expensive materials.
Another approach, disclosed in U.S. Pat. No. 4,740,214, uses an ionic interaction between an ionic polymer in the dyestuff solution and a counter ionic polymer coated onto the textile material. That patent suggests that the ionic interaction of the two polymers, once brought into contact with each other, forms a "skin" about the droplets of the dyestuff solution which adhere to the surface of the fiber. When the printed textile material is steam treated in the fixing process, the skin breaks and the dyestuff is fixed before diffusion can occur. This approach likely would require additional process machinery for pretreating the textile material before dyeing and would add additional steps and thus cost to the dyeing process.
A long-standing need exists for simple and economical improved processes for pattern dyeing of textiles and space dyeing of yarns that can avoid problems such a poor pattern definition and frostiness.